Effect of Chitin Extraction Processes on Residual Antimicrobials in Shrimp Shells

The present study examined the influences of industrial chitin extraction processes on the residual oxytetracycline (OTC) and oxolinic acid (OA) in shrimp carapaces and shells. The drugs were orally administered by catheter to the kuruma shrimp (Penaeus japonicus) and vannamei shrimp (Penaeus vannamei). The shrimps were sampled at 6-h post-dosing and their carapaces and shells were collected and used as raw material in the chitin extraction. Residual OTC levels in raw materials were 9 – 18 fold higher than the maximum residue limit (MRL) (0.2 μg/g). The residual OTC was reduced 10 – 30% by washing treatment. By the acid treatment with HCl, the OTC residues were reduced >98%. The deproteinized material contained negligible levels of OTC. Residual OA levels in raw materials was much higher (134 – 376 fold) than the MRL (0.03 μg/g). The residual OA was reduced considerably (34 – 68%) by washing treatment. By the demineralization, the residual OA could not be detected in both shrimp carapaces, while the levels of OA residues were determined more than MRL in shells. In the deproteinized materials, no residual OA were detected. Finally, residual OTC and OA could not be detected in the chitin materials for both shrimps.